Operating parameter recorders for transportation equipment, such as speed or rpm tachographs for road vehicles and other similar equipment are used to provide a record of the operation of the equipment. For a number of reasons, the operators in direct charge of the equipment may want to conceal the occurrence of certain conditions or to influence the length of time for various periods recorded by the tachograph. Accordingly, the operator may, in certain instances, falsify the recordings made by the recorder. In addition, the recorder itself or the input devices to the recorder are subject to failure, which may not be recognizable from the recordings made by the tachograph.
Some recorders have been developed from purely mechanical arrangements with mechanical clock mechanisms being used to drive the recording medium and mechanical means for moving the recording styli. Other instruments have been developed with electrically and electronically operating instruments having electronic clock and electronic controls of the styli. In either case, one of the most important protective steps is to make sure that there is no interruption of the power supply to the clock mechanism, or the power supply to the styli without recognition of such an interruption. If, for example, the power supply to the clock is interrupted, then the recording medium is not advanced during the interruption. In addition, when the vehicle is stopped, there are not recordings made of speed, distance, engine operation, etc. Therefore when the power to the clock is removed, there are no recordings made whatsoever, but this does not show up on the recording medium. Therefore, if the operator disconnects power to the tachograph, he can manipulate the recordings made on the recording medium. For example, if the vehicle is stopped for a period of one hour but the operator has disconnected the power supply for three quarters of that period, then the stopping period appears to be only one quarter of an hour on the recording medium, as falsified by the operator.
Another method of falsifying recordings made in electronic instruments controlled by electric pulses sent to the tachograph in accordance with engine or vehicle speed is to disconnect the electrical connection between the sending units of the pulses and the recording instrument. By doing so, no speed signals reach the instrument which records on the medium in a fashion to indicate that the vehicle was not moving during this time period. The operator can, therefore, make trips during his shift which are not recorded.
The tachograph itself can be opened in order to permit insertion and removal of the recording medium or chart within the instrument. It is, however, a standard rule that the device should only be opened at the beginning of a workshift to insert the chart and that it not be opened again until the end of workshift, when the chart is removed from the instrument. In some cases, this rule is not complied with as the proper recording of the instrument can be influenced by opening during operation. It is, therefore, important that such openings are clearly and visibly recorded on the recording medium.
Another method of tampering with a tachograph that is, for example, used on a diesel truck is to disconnect the ignition for the truck after it is in motion, which also disconnects the power to the tachograph such that it does not record during such periods.
As described above, there are, therefore, a number of different methods of breaking the circuit line connections to a standard tachograph and, in accordance with conventional construction, the circuit line breakages are very difficult if not impossible to detect.